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Majority of children recover without any complications but neonates, adults, pregnant women and those who are immunocompromised may have more serious complications (1). Complications include:

Pulmonary involvement:

  • between 5 and 14% of adults will have pulmonary involvement
  • pneumonia - particularly in adults; also pneumonia caused by the chicken pox virus itself
    • the risk is increased in pregnant women, the immunocompromised, those with pre-existing lung disease (not including asthma), and smokers (2)

Central nervous system involvement:

  • cerebellar ataxia – usually seen during the recovery period
  • encephalitis:
    • rarely seen in adults (2)
    • classically presenting with ataxia 3 to 4 days after onset of rash, although sometimes up to 8 days, often affecting the cerebellum
    • 80% make a full recovery

Secondary bacterial infections:

  • bacterial infection of lesions
  • common organisms include Staphylococcus aureus or Group A Streptococci
  • skin and soft tissue infection, osteomyelitis, septicaemia or toxic shock syndrome may occur (2)

Haemorrhagic complications

  • pulmonary and gastrointestinal bleeding
  • intra-cerebral haemorrhage
  • disseminated intravascular coagulation (2)

In pregnancy:

  • considerable maternal morbidity
  • congenital varicella syndrome in 10% if infected in first 20 weeks of gestation

Less common complications include

  • arthritis, glomerulonephritis, myocarditis, and purpura fulminans (3)


Last reviewed 07/2021